A virtual reality system generally includes an output device for displaying a virtual space to a user, an input device for receiving a motion of the user, and a control device (computer) for changing the virtual space by reflecting the motion of the user input from the input device thereto and displaying the changed visual space to the output device.
The output device is generally a display device which allows a virtual space to be felt through the sense of sight of a human. The output device may be a computer monitor (screen), which is the simplest example, and may also employ a surrounding screen or a head mounted device to enhance the immersion. The head mounted device is generally worn on the head to surround both eyes of a user. The head mounted device includes displays respectively at the front of both left and right eyes and displays a left eye image and a right eye image respectively on the left and right displays so that a three-dimensional image may be naturally displayed. In particular, in case of the head mounted device, since a user may view only a virtual space, which is a three-dimensional image, implemented by the left and right eye images, the user feels as if he/she is actually in the virtual space, and thus the immersion in a virtual space is more excellent in comparison to any other output device.
In addition, the output device may further include a stereo speaker for giving sounds so that the virtual world may be felt through the auditory sense of a human (sounds may be provided only to the user through an earphone), and may also further include an air blower or a sprayer for giving olfactory or touch stimulations such as wind, fog and smell to enhance the reality of the virtual world.
The input device is used for detecting a motion of the user when the user moves in an actual space for the motion or movement in a virtual space. The input device may use not only simple computer input devices such as a keyboard, a mouse and a joystick but also various devices such as a camera sensor separated from the user to photograph the user, a motion sensor such as an acceleration sensor attached to a body of the user to sense a motion of the user, and a specially designed device such as treadmill or a sensor-mounted chair or vehicle, which allows the user to walk or move on the spot and senses the walking or motion of the user.
However, even though any of such various output devices and input devices is used, in the virtual reality systems which have been developed until now, the user cannot make actual movement such as walking or running in an actual space. It is because that if a simple monitor or a surrounding monitor is used as the output device, the monitor should be fixed to a specific location, and therefore the user cannot play a game unless he/she is at the front of the monitor. In addition, if the head mounted device is used as the output device, the user may freely move theoretically since the display is always at the front of the user even though the user moves in the actual space. However, in this case, the user is able to watch only a virtual space displayed by a display of the head mounted device and is not able to watch the ground or obstacle in a real world (actual space) out of the head mounted device. Therefore, even in this case, the user cannot actually walk or run.
Therefore, the virtual reality system using a head mounted device which has been developed until now just uses an input device such as a specific chair or vehicle which allows a user to make a motion just on the spot, but such an input device does not reflect a feeling of walking or moving of the user in the actual space, which deteriorates the fun and reality of a game and is also not sufficiently helpful for actual exercise or training of the user.
Meanwhile, a device having a small display for displaying information at the front of the eye of a user so that the user may watch the information provided by the display together with a real world has been proposed, for example ‘Google glass’ recently released. If this device is used as the output device, a user may make active movement such as walking and running since the user may watch the ground and obstacles in the actual space. However, even though the Google glass is useful for watching auxiliary information in addition to a real world seen by the user, a system using the Google glass gives very deteriorated immersion in a virtual space (when the auxiliary information is regarded as an image of the virtual space) in comparison to the above head mounted device, and thus the Google glass cannot be regarded as a true virtual reality system.
Here, the Google glass may also be regarded as a head mounted device since it is worn on the head, but in this specification, the ‘head mounted device’ just means a device capable of showing only a virtual space, and this will also be called a ‘immersive’ head mounted device if it should be distinguished from a device such as a Google glass capable of showing auxiliary information in addition to a real world.
In a virtual reality system which has been developed until now, it is impossible to allow the immersion in a virtual space to consist with an actual movement of a user in an actual space.